JPH11273562A - Manufacture of color television picture tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a color television picture tube by employing lens for exposure of a color television picture tube and capable of improving the image quality of the resultant color television picture tube and the productivity. SOLUTION: The correction lens to be employed for panel exposure process is a lens with discontinuous faces constituted of flat and small lens faces having a prescribed three-dimensional inclination and arranged in M-lines and N-rows and the correction lens is manufactured by molds 19 formed by fixing mold partition units 20, each of which is formed by arranging M-pieces of small faces 20a for forming the small lens faces in a row, tightly in parallel to one another in N-pieces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for manufacturing a color picture tube, and more particularly to an exposure process using a correction lens when forming a phosphor screen pattern.

[0002]

2. Description of the Related Art Generally, phosphor dots of three colors of red, green and blue are regularly formed on the inner surface of a shadow mask type color picture tube panel via a black matrix (opening of a black absorbing layer). The phosphor screen is usually formed by a photographic method using an exposure apparatus.

As shown in FIG. 4, the above exposure apparatus deflects a light source unit 1 and an exposure light beam 7 emitted from the light source unit 1 from an electron gun when an actual color picture tube is used and deflects it by a deflecting magnetic field. Exposure correction lenses 2 and 3 for approximating the trajectory of the electron beam to be irradiated and a light amount correction filter 4 have a basic configuration. In this exposure apparatus, a panel 5 on which a shadow mask 6 is mounted is installed so as to face the correction lens 3, and a photosensitive film or a phosphor slurry film formed on the inner surface of the panel 5 is applied to the correction lenses 2, 3 and 3. Exposure light beam 7 through light amount correction filter 4 and shadow mask 6
Exposure.

The correction lens 3 needs to have a correction function for approximating the exposure light beam 7 to the trajectory of the electron beam for each exposure surface having a different distance from the light source unit 1 as shown in FIG. A discontinuous surface lens having a plurality of adjacent mirror surfaces, each of which is three-dimensionally inclined in a predetermined direction, that is, a discontinuous surface on which so-called segments 3a are arranged in a column direction.

The segment 3a of the correction lens 3 is 8 [m
m] It is a square having four dimensions, and in a lens used for general exposure, 588 (3 rows × 28 columns) of these segments 3a are regularly arranged in a grid pattern. The correction lens 3 having such a shape is manufactured by molding a thermoplastic resin or an ultraviolet curable resin using a molding die.

[0008] As shown in FIG. 8, the above-mentioned molding die has M × N mold dividing blocks 11 inside an assembly fixed frame 10.
Are inserted in the arrangement of M rows × N columns, and the row direction pressing plate 12 pressed in the row direction X by screwing in the row direction pressing bolts 14 and the column direction Y by screwing in the column direction pressing bolts 17. Receiving the pressing force from the pressed column-direction pressing plate 13, it is fixed by the static friction force.

Each mold division block 11 has a mirror plane 11a (small plane for molding) for forming a segment 3a of the correction lens 3 on one end surface thereof. It has a unique three-dimensional inclination so that a unique optical correction is performed at the position to be set. For example, if the location where each mold division block 11 is set is (i, j), the mirror plane 11a of each mold division block 11 is θx in the row direction x.
(I, j) and θy (i, j, y) in the column direction y.
j).

On the other hand, the sub-mold part 9 has a container shape having an opening corresponding to the fixing frame 10 for assembly, and has a resin injection port 18 on one side.

The above-mentioned molding die comprises a main die part 8 and a sub die part 9.
After the molds are combined and the mold is clamped, a required resin is injected from the resin injection port 18 into the molding space between each mirror plane 11a of each mold division block 11 and the inner surface of the sub-mold portion 9. Thus, the correction lens 3 can be formed.

However, the mold dividing block 11 is
To tighten and fix a large number of blocks in a grid at the same time, to prevent unbalanced distortion and cracking of the blocks, and to prevent the blocks from coming off when peeling off the lens after molding, It is necessary to use a cemented carbide or a hard and brittle material for the purpose of minimizing variations in the dimensions. In order to form an accurate angle and a fine mirror surface using these materials, all of the 588 blocks have to undergo a number of steps such as roughing, finishing, and polishing. Further, it is necessary to arrange a large number of blocks at predetermined predetermined positions with high precision and to tighten them uniformly. For this reason, there is a problem that it takes a lot of time and cost to manufacture the correction lens.

In order to solve such a problem, Japanese Patent Laid-Open Publication No.
Japanese Patent Application Laid-Open No. 217498/1994 and Japanese Patent Application Laid-Open No. 6-314541 propose a method of molding a correction lens using a single mold having a plurality of flat surfaces formed on the surface. This makes it difficult to mold the mold itself, and there is a problem that it is not possible to respond quickly and easily to mold design changes and molding errors.

On the other hand, as shown in FIG. 3, since there is a step 3b in the correction lens 3, a shadow of the step is projected on the screen of the color picture tube at the time of exposure, and the shadow is completed. There is a problem that it appears in the pipe. Therefore, during the exposure, it is necessary to swing the correction lens two-dimensionally in a pattern proportional to the dimension of the segment 3a as shown in JP-A-50-78273 or JP-A-8-162221. is there.

However, as shown in FIG. 5, when the correction lens 3 is swung in the direction of an arrow 52, the exposure light beam 7 passing through the hole of the shadow mask moves to a desired place 51 where a black matrix or a phosphor dot is to be formed. Instead of performing the exposure at all times, the exposure location fluctuates as indicated by an arrow 53 substantially in proportion to the swing distance and the difference between the inclination angles of the adjacent segments 3a. As a result, in the process of forming the black matrix, the boundary lines of the holes of the black matrix tend to be not smooth but jagged or to be distorted into a diamond instead of a clean circle or ellipse. In a completed color picture tube, the influence of the jagged shape of the former appears as so-called mattering in which a display image looks dull. The effect of the latter shape distortion is the so-called lack of self-color, in which the electron beam does not completely strike the predetermined phosphor, or the so-called other-color strike, in which the electron beam strikes the phosphor next to the predetermined phosphor. It appears as a phenomenon in which the margin is impaired, that is, a decrease in the margin.

In the step of forming the phosphor dots,
When the phosphor dots become too large and protrude into the adjacent black matrix, so-called protrusions, or when the output of the light source unit is dropped to make the phosphor dot size not protrude into the adjacent black matrix, the phosphor dots are The problem of easy peeling-off, a phenomenon of so-called dot dropping, was also likely to appear.

[0015]

In the above prior art, in order to solve the problem of the matting and the drop of the dot, when the size of the segment is reduced, for example, the conventional segment of 8 [mm] on one side is reduced to one half of the side. When it is set to 4 [mm], the required mold division blocks are exponentially swollen to 2352 (42 rows × 56 rows). Therefore, it took an enormous amount of time and cost, and was not realistic. Therefore, conventionally, the difference between the inclination angles of adjacent segments has been designed to be as small as possible. Therefore, for models that require a large amount of correction, such as a color picture tube with a large deflection angle or a color picture tube with a flat screen surface, the correction amount is not enough and multiple auxiliary aspherical lenses can be added. I had no choice. However, there remains a problem that the accuracy of forming the phosphor dots and the exposure illuminance are reduced and the exposure time is lengthened.

Accordingly, an object of the present invention is to provide a method of manufacturing a color picture tube using a color picture tube exposure lens which solves the above-mentioned problems of the prior art and improves the image quality and productivity of the color picture tube. Is to do.

[0017]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a discontinuous device in which a plane small lens surface or a curved small lens surface having a predetermined three-dimensional inclination is arranged in M rows.times.N columns. N mold division units, each of which is a surface lens, and is formed by arranging M molding small planes or small curved surfaces for molding the small lens surface in a line, are arranged in parallel with each other and in a close contact state. Exposure step of forming a black matrix and a phosphor film by irradiating light radiated from a light source to a photosensitive film on the inner surface of a front panel through a correction lens formed by a mold fixed and formed by a mold and a shadow mask. (Claim 1).

Further, in the mold, the N mold dividing units are inserted into the fixed frame for assembly, and a pressing bolt is screwed from a side wall of the fixed frame for assembly to form the mold divided unit. It is preferable that it is fixed so as to be pressed (claim 2).

The small molding surface or the small curved surface is a square or a rectangle, and the dimension of one side is 2 [mm].
It is preferable that the dimension of the other side is not less than 4 [mm] and not more than 2 [mm] and not more than 8 [mm].

In the mold for forming the correction lens according to the present invention, M small flat surfaces or curved surfaces can be collectively formed in a relatively large flat mold dividing unit, and the side surfaces of the mold dividing unit are adjacent to each other. Since the cutting process can be performed in accordance with the die dividing unit to be manufactured, the number of man-hours for manufacturing the main die portion can be significantly reduced, and the die cost can be reduced.

When assembling the mold, a flat plate-shaped
By inserting the mold dividing units into the assembly fixing frame, M molding small planes can be formed at once, so that all the molding small planes can be arranged quickly, and the main mold part can be formed. Reduces the number of assembly steps.

Furthermore, since the relatively large flat plate-shaped mold dividing unit is inserted into the fixing frame for assembly, the mold dividing blocks each having a small molding surface in the conventional mold are inserted into the fixing frame for assembly. There is almost no risk of inconvenience caused by foreign matter being bitten as in the case of assembly by assembling.
For this reason, precision work in a clean room is not particularly required, so that the manufacturing cost can be reduced together with the reduction in the number of assembly steps.

Further, in the above invention, the mold dividing unit forms M small flat surfaces on the flat plate and grinds the side surfaces thereof in units of the arrangement direction so as to match the side surfaces of the adjacent mold dividing blocks. Since it is possible to perform the machining, not so high dimensional accuracy is required for the machining, so that the mold dividing unit can be formed of a soft metal capable of forming a mirror surface by the machining.

As a result, the material cost is considerably reduced as compared with the hard and brittle material which is the processing material of the metal split block in the conventional die, and the processing of the small flat surface for molding is remarkably facilitated. Time is also reduced.

By forming a correction lens using the above-mentioned mold, an exposure correction lens having a segment size capable of realizing a sufficiently small swing range at the time of exposing the screen surface of a color picture tube is provided at a practical time and cost. Further, by forming the phosphor screen using the correction lens having a segment size capable of realizing a sufficiently small swing range at the time of exposing the screen surface of the color picture tube, problems such as matting and dot dropout can be solved. Can be resolved. That is, the image quality and productivity of the color picture tube can be improved.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic exploded perspective view of a molding die for a correction lens according to an embodiment of the present invention. The main mold portion 19 of this molding die has one row in the row direction X, N = 5.
Six small molding planes 20a are provided with M = 42 mold division units 20 integrally formed on one end surface of the flat plate member. Each molding small surface 20a is 4 [mm] × 4 [m
m], and has a gradient θx in the row direction x and a gradient θy in the column direction y with respect to the substrate plane, and the three-dimensional gradient is the address (i, j) corresponding to the correction lens 3. ) Is set to

The row direction pressing plate 12 in the conventional mold is
And, the row direction pressing bolt 14 is not provided. Therefore, the width of the assembly fixing frame 10 in the direction x is reduced by substantially the thickness of the row direction pressing plate 12. In other words, the distance between the opposing surfaces in the row direction x of the assembly fixing frame 10 is set to be slightly larger than the length of the mold division unit 20 so that the mold division unit 20 is inserted in a fitted state. Has become.

In the above-mentioned molding die, as shown by arrows in FIG. 1, M = 42 die dividing units 20 are fitted into the fixed assembly frame 10 in a predetermined order, and all the die dividing units are set. After the insertion of the mold 20 is completed, each mold dividing unit 20 is pushed in the column direction via the row direction pressing plate 13 by screwing the row direction pushing bolt 17, and each mold dividing unit 20 is subjected to a static friction force. , The assembly of the main mold part 19 is completed. As shown in FIG. 2, a molding space 21 surrounded by each molding small plane 20a and the inner surface of the sub-molding portion 9 is joined together with the sub-molding portion 9 and the main mold portion 19. The required resin 22 is injected from the resin injection port 18 into the inside, and a correction lens is manufactured by resin molding.

Mold dividing block 11 in a conventional mold
In order to perform grinding and polishing that requires extremely high dimensional accuracy on a relatively small upper section of the shaft having a rectangular cross section, it was necessary to use a hard and brittle material. -Shaped relatively large mold splitting unit 2
In addition to forming M = 56 small forming planes 20a in 0, the side surfaces of each mold dividing unit 20 can be ground in rows in accordance with the side surfaces of the adjacent mold dividing units 20 in the column direction y.

As a result, it is possible to use a soft metal such as an aluminum-magnesium alloy, oxygen-free copper, or electroless nickel as a material of the mold dividing unit 20, and material costs are considerably reduced. Further, by forming M = 56 small forming planes 20a at once and using a soft metal as a raw material, processing of the forming small plane 20a is greatly facilitated. Further, the metal dividing unit 20
Can be ground in rows, and the column-direction pressing plate 13 and the column-direction pressing bolts 17 are not required, so that the man-hours for manufacturing the main mold portion 19 is significantly reduced.

In this embodiment, 4 [mm] × 4
In order to create a correction lens having a segment of [mm], a mold is constituted by N = 42 mold dividing units, but a conventional mold has a 4 [mm] × 4 [mm] segment. In order to create a correction lens having the same, 2352 mold division blocks are required, which is not very realistic.

FIG. 6 is a diagram showing the relationship between the segment 3a and the swing range 61, showing that the point at the lower left corner of the segment 3a swings within the swing range 61. By using the correction lens having the 4 mm × 4 mm segments formed as described above for exposing the phosphor screen, the swing width of the correction lens is reduced as shown in FIG. 6), about 5.6 [mm] × 5.6 [m], which is a half of the conventional about 11.3 [mm] × 11.3 [mm] shown in FIG.
m].

FIG. 7 shows the effect of the method for manufacturing a color picture tube according to the present invention in comparison with a conventional manufacturing method. Here, the matting evaluation value (curve 24) was determined by visual evaluation. Each of the indicators has a level 1 "V
"Level that hinders DT work", level 2 is "VDT
Conventionally, the level which is worrisome during the work, the level 3 is "the level which is not defective, but unevenness can be detected", the level 4 is "the level where slight unevenness can be detected", and the level 5 is "level where no unevenness can be detected" The average value of the evaluation values is shown for each of the examples and the inventions A, B and C. Also, the dot drop defect ratio (curve 25) is 100
[%] Is shown as a relative value. In FIG. 7, it can be seen that the method of manufacturing a color picture tube according to the present invention has improved matting and dot dropping as compared with the conventional manufacturing method. Further, the segment size is 4 [mm] × 4 [m
m] and 2 [mm] × 2 [mm], no significant difference was observed in the effect. In addition, one auxiliary lens is added, and the segment size is 4 [mm] × 8 [m
m] also showed an improvement effect.

In the above embodiment, the auxiliary mold portion 9 is described as having a space for molding, but this portion is replaced by a glass substrate and a spacer.
After the molding, the glass substrate and the molded lens may be formed into an integrated shape. Further, although the correction lens segment and the corresponding mold portion are described as flat surfaces, similar effects can be obtained even if this portion is a curved surface.

[0036]

As described above, according to the present invention,
A correction lens having a small segment size and a reduced difference in the angle between adjacent segments can be easily manufactured, and the swing range of the correction lens in the exposure process can be reduced, resulting in a matter of matting in a color picture tube. It is possible to solve the problems such as dot dropping and the like, and to provide a color picture tube with excellent image quality.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a molding die of a correction lens according to the present invention.

FIG. 2 is a cross-sectional view showing a forming process of a correction lens.

FIG. 3 is a perspective view showing a correction lens.

FIG. 4 is a conceptual diagram showing an exposure process of a panel for a color picture tube.

FIG. 5 is a conceptual diagram showing a swinging state of a correction lens in an exposure step.

FIG. 6 is a conceptual diagram showing a swing range of a correction lens in an exposure process.

FIG. 7 is a diagram showing an evaluation result of image quality of a color picture tube manufactured according to the present invention.

FIG. 8 is a perspective view showing a molding die for a conventional correction lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source part 3 Correction lens 5 Panel 6 Shadow mask 7 Exposure light beam 10 Assembly fixed frame 13 Press plate 17 Press bolt 19 Main mold part 20 Mold division unit 20a Molding small plane

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shingo Matsumoto 1-1, Sachimachi, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd. Inside the corporation

Claims (3)

[Claims] A flat lens surface or a curved lens surface having a predetermined three-dimensional inclination is a discontinuous surface lens arranged in M rows × N columns, and is used to form the small lens surface. A correction lens molded by a mold formed by fixing N mold splitting units formed by arranging M molding small planes or small curved surfaces in a line in a mutually parallel manner and in close contact with each other. A method of manufacturing a color picture tube comprising an exposure step of forming a black matrix and a phosphor film by irradiating light emitted from a light source to a photosensitive film on the inner surface of a front panel through a shadow mask. 2. The mold according to claim 1, wherein the N mold dividing units are inserted into an assembly fixing frame, and a pressing bolt is screwed from a side wall of the assembly fixing frame to form the mold dividing unit. 2. The method according to claim 1, wherein the tube is fixed so as to be pressed. 3. The small flat surface or the small curved surface for molding is a square or a rectangle, and the dimension of one side is 2 mm or more and 4 mm or less, and the dimension of the other side is 2 mm or more and 8 mm or more.
2. The method for producing a color picture tube according to claim 1, wherein [mm] or less.